How is a mortgage amortization schedule calculated?

A schedule is built month by month: multiply the current balance by the monthly interest rate to get that month's interest, subtract the interest from the fixed monthly payment to get that month's principal, then subtract the principal from the balance to get the new balance. Repeat for every month of the loan. Our calculator does exactly this for every month of your term and lets you download the full result as a CSV.

How do you calculate monthly mortgage payment with amortization?

Enter your loan amount, interest rate, and term into the formula M = P × [r(1+r)^n] / [(1+r)^n − 1]. For a $400,000 loan at 6.5% over 30 years, that works out to roughly $2,528/month in principal and interest — before taxes, insurance, or HOA. Use the calculator above to get an exact figure for your own numbers, including escrow costs.

How can I build my own mortgage amortization calculator?

At its core you need three things: the standard amortization formula above to get the fixed monthly payment, a loop that walks month-by-month subtracting interest and principal from the balance, and a way to layer in extras (PMI, escrow, additional principal payments). If you want to see the exact logic, our methodology page walks through the math we use, formula by formula.

Why does my amortization schedule show more interest than I expected in year one?

On a 30-year loan, it's normal for 60-75% of your first year of payments to go toward interest rather than principal — the balance is at its highest point, so the interest portion (balance × rate) is also at its highest. This flips gradually over the life of the loan, which is exactly why extra principal payments made early save so much more interest than the same extra payment made in year 25.

Is this mortgage amortization calculator free to use?

Yes — every calculator on this site, including the full amortization schedule, CSV export, and every cluster calculator (extra payments, recast, balloon, refinance) is free with no signup required.

Does this calculator account for property taxes and insurance?

Yes — open the "Taxes, Insurance, HOA & PMI" section above to add your annual property tax, homeowners insurance, monthly HOA dues, and PMI rate. The "Estimated Monthly Payment" figure at the top includes all of these; the "Principal & Interest" line below it shows the loan-only portion separately.

Why did my down payment percentage affect the interest rate options?

This calculator doesn't automatically adjust your rate for down payment size — you enter the rate you were quoted or expect. In the real world, though, a smaller down payment (below 20%) usually triggers PMI and can nudge your quoted rate slightly higher, since the lender is financing a larger share of the home's value.

Can I use this calculator for a rental or investment property?

The math is identical — enter the investment property's price, expected rate, and term. Just note that lenders typically charge somewhat higher rates and require larger down payments for non-owner-occupied properties, so use the actual terms quoted for an investment loan rather than owner-occupant rates.

Mortgage Amortization Calculator

Written by Sukie Gao · Last reviewed October 16, 2026

Educational estimate, not financial advice. Every number on this page is generated by our calculator from the inputs you provide. Confirm final figures with a licensed lender before making a financial decision — see our Terms of Service.

A mortgage amortization calculator shows exactly how each payment splits between interest and principal, every month, for the life of your loan. Use it to:

Compare loan offers — see how rate, term, and down payment change your real cost before you buy.
Model extra payments — find out how much time and interest a lump-sum or monthly extra payment saves.
Add PMI, taxes, insurance & HOA — get your true all-in monthly payment, not just principal and interest.
Get the full schedule — every month for the life of the loan, downloadable as a CSV.

Enter your numbers below to generate your schedule.

↓ Open the Calculator

Try the Mortgage Amortization Calculator

Home Price

Down Payment (20%)

Down payment $80,000 · loan amount $320,000

Interest Rate (%)Loan Term

First Payment

Extra Payments (optional)

Extra Monthly

Extra Once a Year

One-Time Lump Sum

Lump Sum in Payment #

The yearly extra is applied at every 12th payment. Payment #12 falls in Sep 2027.

Pay biweekly instead of monthly (26 half-payments/year)

Taxes, Insurance, HOA & PMI

Property Tax / yr

Home Insurance / yr

HOA / month

PMI Rate (%)

PMI is waived — down payment is 20% or more.

Estimated Monthly Payment

$2,506

Principal & Interest

$2,023

Taxes + Insurance + HOA + PMI

$483

Total Interest Paid

$408,142

Payoff Date

Sep 2056

Total of All Payments

$902,142

Number of Payments

360

Remaining Balance Over Time

Hover the chart to see balance by year

Year	Principal Paid	Interest Paid	Ending Balance
1	$3,577	$20,695	$316,423
2	$3,816	$20,455	$312,607
3	$4,072	$20,200	$308,535
4	$4,345	$19,927	$304,191
5	$4,636	$19,636	$299,555
6	$4,946	$19,325	$294,609
7	$5,277	$18,994	$289,332
8	$5,631	$18,641	$283,701
9	$6,008	$18,264	$277,694
10	$6,410	$17,861	$271,284
11	$6,839	$17,432	$264,444
12	$7,297	$16,974	$257,147
13	$7,786	$16,485	$249,361
14	$8,308	$15,964	$241,053
15	$8,864	$15,407	$232,189
16	$9,458	$14,814	$222,732
17	$10,091	$14,180	$212,641
18	$10,767	$13,505	$201,874
19	$11,488	$12,784	$190,386
20	$12,257	$12,014	$178,129
21	$13,078	$11,193	$165,051
22	$13,954	$10,317	$151,097
23	$14,888	$9,383	$136,208
24	$15,886	$8,386	$120,323
25	$16,949	$7,322	$103,373
26	$18,085	$6,187	$85,289
27	$19,296	$4,976	$65,993
28	$20,588	$3,683	$45,405
29	$21,967	$2,305	$23,438
30	$23,438	$833	$0

How This Mortgage Amortization Calculator Works

Every fixed-rate mortgage is amortized the same way: your lender calculates one payment amount that stays constant for the life of the loan, but the mix of interest and principal inside that payment shifts every month. In month one, most of your payment is interest — you're borrowing against the full loan balance, so the interest charge (balance × monthly rate) is at its highest point. As you chip away at the balance, the interest portion shrinks and the principal portion grows, even though the total payment doesn't change. That shifting split is what "amortization" means, and it's why paying extra toward principal early in the loan saves far more interest than the same extra dollar paid in year 25.

This tool runs that exact month-by-month math for you — 360 rows for a 30-year loan, 180 for a 15-year loan — and lets you layer in the variables that actually affect what you pay: private mortgage insurance (PMI) if your down payment is under 20%, property taxes and homeowners insurance if you escrow them into your payment, HOA dues, and any extra principal payments you plan to make. Toggle biweekly payments to see how simply splitting your payment in half every two weeks (26 half-payments = 13 full payments a year) accelerates payoff without changing your budget much.

You can start from a home price and down payment or type the loan amount directly, pick any term from 5 to 40 years, and set the month of your first payment so every row in the schedule carries a real date. Extra principal can go in three ways at once: a fixed amount every month, a larger amount once a year, and a one-time lump sum in whichever payment you choose. With less than 20% down, the results show when you can ask your servicer to cancel PMI (80% of the original value) and when it must end automatically (78%), the two points the CFPB describes. The full schedule downloads as a CSV that opens in Excel or Google Sheets, or prints straight from the page.

Worked Example: $400,000 Home, 20% Down, 6.5%, 30 Years

Say you're buying a $400,000 home with 20% down ($80,000), leaving a $320,000 loan at 6.5% over 30 years. Your principal-and-interest payment comes out to roughly $2,022/month. Over the full 30 years you'll pay about $407,900 in interest — more than the original loan amount — on top of repaying the $320,000 principal, for a total of just over $727,900 paid to borrow $320,000.

Now add just $200/month in extra principal payments from day one. The loan payoff moves up by roughly 5.5 years, and total interest drops by around $70,000. That's the entire point of running your numbers through an amortization calculator instead of just looking at the monthly payment quoted by a lender: the monthly number tells you what you can afford today, but the schedule tells you what the loan actually costs over its life — and how much control you have over that cost.

Ways to Pay Off Your Mortgage Faster

Every one of these strategies works by increasing the principal portion of what you pay, which is the only lever you have once your rate and term are locked in:

Extra monthly payments — even a modest, consistent amount compounds significantly over a 30-year term. Model your own numbers on our extra payments calculator.
Biweekly payments — splitting your payment in two every two weeks results in one extra full payment per year, almost painlessly.
A lump-sum recast— if you come into money (bonus, inheritance, home sale proceeds) and don't want to refinance, a mortgage recast re-amortizes your existing balance into a lower payment at your current rate.
Refinancing — if rates have dropped meaningfully since you took out your loan, run the numbers on our refinance calculator to see your real break-even point after closing costs.
Dropping PMI early — once your loan-to-value ratio hits 80%, you can usually request PMI removal rather than waiting for automatic cancellation. See how extra payments accelerate that date on our PITI calculator.

What Determines Your Interest Rate

The rate you enter above is the single biggest lever in this whole calculation — a 1-point difference on a $400,000, 30-year loan changes your monthly payment by roughly $250 and your lifetime interest by tens of thousands of dollars. Lenders price your rate off a handful of factors you can influence before you ever apply:

Credit score. The spread between a 620 borrower and a 760+ borrower is routinely 0.5-1 full percentage point on a conventional loan. Pulling your score up even one tier before you shop can be worth more than negotiating with a single lender.
Down payment / loan-to-value (LTV).Putting down 20% instead of 5% not only removes PMI (see below) but often earns a modestly better rate, since the lender's exposure if you default is lower.
Debt-to-income (DTI) ratio. Lenders compare your total monthly debt payments (including the new mortgage) to your gross income. For loans sold to Fannie Mae, the maximum is 36% when manually underwritten, up to 45% with qualifying credit and reserves, and 50% through Desktop Underwriter (Selling Guide B3-6-02). Staying well under your program's limit widens your rate options.
Loan term and type.Shorter terms price lower because the lender's money is at risk for half as long. In Freddie Mac's survey for the week of October 8, 2026, the 15-year fixed averaged 6.73% against 7.40% for the 30-year, 0.67 points lower. FHA, VA, and USDA loans carry their own rate and mortgage-insurance rules that can price better or worse than a conventional loan depending on your situation.
Points and lender credits.You can pay upfront "discount points" to buy your rate down, or take a slightly higher rate in exchange for a lender credit toward closing costs — run both scenarios through this calculator with different rate/loan-amount combinations before deciding which trade is worth it for how long you plan to keep the loan.

None of these factors are inputs this calculator can look up for you — they come from your actual application — but changing the rate field above to test a best-case and worst-case scenario before you apply is exactly how to use this tool to negotiate from an informed position.

Reading Your Amortization Schedule

The table above groups your loan by year, with a "Show months" toggle to expand any year into its individual monthly rows. Each row breaks your payment into the same five pieces every lender's schedule uses:

Principal paid — how much of that year's payments reduced your loan balance.
Interest paid — the cost of borrowing for that year, calculated on whatever balance remained at the start of each month.
Extra payment — any additional amount you added beyond the required payment, which comes entirely off principal.
PMI — private mortgage insurance, shown only while your loan-to-value ratio sits above the cancellation threshold.
Ending balance — what you'd still owe if you sold or refinanced at the end of that year.

Watch the crossover point where the principal column overtakes the interest column — on a typical 30-year loan at today's rates, that happens somewhere between year 15 and year 20. Everything paid before that crossover is weighted much more heavily toward interest than most borrowers expect, which is exactly why extra payments made in the first five to ten years do so much more work than the same dollar amount paid later. For a real 360-row example read column by column, with the milestones to look for, see our guide to the mortgage amortization schedule.

How We Calculate These Numbers

Every figure on this page comes from the standard fixed-rate amortization formula: M = P × [r(1+r)ⁿ] / [(1+r)ⁿ − 1], where P is your loan principal, r is your interest rate divided by 12, and n is your total number of monthly payments. We generate a full month-by-month schedule from that formula rather than approximating, so the numbers you see here match what you'd get from a closing disclosure or lender-provided amortization table for the same inputs. For background on how rates and PMI rules work more broadly, see Freddie Mac's Primary Mortgage Market Survey and the CFPB's guidance on PMI cancellation. For a full breakdown of the formula and every variable this calculator supports, see our calculation methodology page.

Every Calculator on This Site

Each calculator below answers one specific question about a mortgage, and each comes with a guide to that question. Reverse mortgages, where the balance grows instead of shrinking, have their own hub at the reverse mortgage calculator.

Mortgage amortization calculators

Reverse mortgage calculators

Frequently Asked Questions

Mortgage amortization is calculated by splitting each monthly payment between interest (the balance times your monthly rate) and principal (whatever's left of the payment). Early on, most of your payment is interest because the balance is largest; as the balance shrinks, more of each payment goes to principal. The standard formula is M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the loan amount, r is your monthly interest rate (annual rate ÷ 12), and n is the number of monthly payments.